My goal in making the first edition freely available five years after publication was twofold. First, I wanted to reach the widest possible audience, especially among poor students. Second, I am a pragmatic libertarian on free culture and free software issues; I think that many publishers (especially of music and software) are too defensive of copyright. (My colleague David MacKay found that putting his book on coding theory online actually helped its sales. Book publishers are getting the message faster than the music or software folks.) I expect to put the whole second edition online too in a few years.